Photo 2. Plants showing pink, rolled, leaves typical of pineapple mealybug wilt disease. The 'wilt' symptoms are due to root decay, caused by virus infection.
Photo 3. The two stunted plants in the foreground are showing symptoms of pineapple mealybug wilt disease.
Mealybug wilt of pineapple
Worldwide; in all the major pineapple growing areas: Asia, Africa, South, North and Central America, the Caribbean, Oceania. In has been recorded from Australia, Cook Islands, Fiji. Plants from American Samoa and Samoa found to be infected for two pineapple mealybug wilt-associated viruses (PMWaVs) when maintained in the USDA-ARS National Clonal Germplasm Repository, Hilo, Hawaii.
Pineapple and Pseudoananus. The latter is commonly called the false pineapple, not grown commercially (https://commons.wikimedia.org/wiki/File:Pseudoananas_sagenarius_(8400437895).jpg).
Pineapple wilt occurs worldwide, is important, although often variable in plantations. This is because the disease depends on the presence of the virus(es), the number of mealybugs present, the length of time they feed, and the presence of ants. Trials in Hawaii showed that if pineapple wilt occurs during the first 3 months of the plant crop, average fruit weight is reduced by 55% compared to plants that remain virus free.
Look for early symptoms - reddening of leaves about halfway up the plant. Look for a change of colour from red to pink, a downward roll of the leaves and dieback of the tip as the leaves collapse. Look for Dysmicoccus mealybugs which spread the wilt disease.
Management of pineapple wilt is difficult. It depends on at least four factors: i) clean (virus-free) planting material; ii) removal of weeds; iii) mealybug control; and iv) plant density.
There are a large number of predators and parasitoids of Dysmicoccus brevipes, including ladybird beetles, particularly Cryptolaemus species (see Fact Sheet no. 395), and wasps (encyrtids). In many countries, biological control is effective when ants (Pheidole, Iridomyrmex and Solenopsis) are controlled (see Fact Sheet nos. 361, 362&363).
Importation of pineapple plants for planting from countries where pineapple wilt occurs should not be permitted unless they are kept under observation in closed post-entry quarantine and tested for pineapple viruses (ampeloviruses and badnaviruses, in the Closteroviridae and Caulimoviridae families, respectively). For fresh fruit, an import risk analysis should be considered where countries are vulnerable to this serious disease, its mealybug vectors and associated ants. Conditions invariably require fresh pineapples to be de-crowned, from registered commercial plantations, fumigated pre-shipment, and inspected on arrival. CULTURAL CONTROL
The control measures recommended below are for the control of the mealybug, and also for the control of Pineapple mealybug wilt-associated virus(es) that they are thought to spread.
AUTHOR Grahame Jackson
Information from Sether DM et al. (2001) Differentiation, distribution, and elimination of two different Pineapple mealybug wilt-associated viruses found in pineapple. Plant Disease 85:856-864. (https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS.2001.85.8.856); and J Hu (2002) Detection, Characterization, and Management of Pineapple Mealybug Wilt-Associated Viruses. (http://www2.hawaii.edu/~johnhu/pineapple.pdf); and Subere C et al. (2009) Vector transmission of Pineapple mealybug wilt associated virus-2 by Dymiococcus neobrevipes and Peudococcus lngispinus in Hawaii. Phytopathology 99: S125; and from Subere CVQ et al. (2011) Transmission characteristics of pineapple mealybug wilt associated virus-2 by the grey pineapple mealybugs Dysmicoccus neobrevipes in Hawaii. Proceedings 7th International Pineapple Symposium. Eds.: Abdullah H et al. Acta Hort. 902, ISHS. (https://www-actahort-org.ezproxy.library.uq.edu.au/members/showpdf?session=12083). Photos 1&2 United States National Collection of Scale Insects Photographs, USDA Agriculture Research Service, Bugwood.org. Photos 3&4 United States National Collection of Scale Insects Photographs, USDA Agricultural Research Service, Bugwood.org.
Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/185: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Secretariat of the Pacific Community.
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